IP final Round 2

All variables affecting the acquisition and quality of a radiographic image can be categorized into one of ___ types of variable

8

3 multiple choice options

Positioning of the patient and patient motion are both most accurately categorized as _____ variables.

Geometrical

3 multiple choice options

In projection geometry, which of the following portions of the x-ray beam diverges isotropically?

All primary rays except the central ray

3 multiple choice options

The entire distance traversed by the central ray is known as the

SID

3 multiple choice options

The absorption rate of an x-ray beam through a particular thickness of soft tissues is

Exponential

3 multiple choice options

Of the following, the most likely initial interaction of diagnostic-energy x-rays in high Z-number materials such as bone and contrast agents is

Photoelectric interaction

3 multiple choice options

Mathematically, subject contrast in the remnant beam signal is best thought of as the _____ between two adjacent areas of different x-ray intensities.

Divided ratio

3 multiple choice options

A body part that is 5 cm thinner than average requires _____ for radiographic technique.

15% less kVp

3 multiple choice options

Bone shows up with high contrast on a radiograph primarily because of its

Atomic number

3 multiple choice options

Which of the following is not a reason why higher kVp levels result in reduced image contrast?

Compton interactions increase in number

3 multiple choice options

Compared to the effects of field size and patient size, the set kVp is a relatively _____ factor in the prevalence of scatter radiation.

Minor

3 multiple choice options

The intensity of the entire x-ray beam is doubled, such that twice as many photons pass into the patient. The ratio between the number of photoelectric interactions and the number of Compton interactions taking place will

Remain equal

3 multiple choice options

What is the prevalent interaction of x-rays in soft tissue at high kVp levels?

Compton

3 multiple choice options

Scatter radiation reduces subject contrast in the signal reaching the image receptor because

It lays down a "blanket" of roughly even exposure across an area of the image receptor

3 multiple choice options

In the remnant x-ray beam signal, even if no scatter radiation is present at all, increasing the kVp still _____ due to the increasing number of tissues penetrated.

Lengthens the gray scale

3 multiple choice options

Which type of noise becomes visible in the image when there is an insufficient amount of signal reaching the image receptor?

Quantum mottle

3 multiple choice options

Generally, for an image with insufficient visibility of some details, which of the following should be adjusted first?

Contrast

3 multiple choice options

All of the following would be classified as sources of material mottle except

Grids

3 multiple choice options

A radiograph of an aluminum step wedge demonstrates only very small differences from one density (brightness) to the next. This image possesses

1. low contrast

11. Short gray scale

111. Low density

1 only

3 multiple choice options

The ideal degree of brightness for any image would be a(n) _____ level.

Intermediate

3 multiple choice options

In the broadest sense, anything that impedes full visibility of the details in an image may be classified as

Noise

3 multiple choice options

Remaining within the practical range of diagnostic brightness (density) values (that is, without going to extremes), a radiographic image's

Average brightness can be changed up or down without changing its contrast

3 multiple choice options

Most radiographic images are viewed as _____ images.

Negative

3 multiple choice options

Extremely long gray scale in an image can lead to a loss of information because

Slightly different shades of gray can not be distinguished from one another

3 multiple choice options

In the digital age, _____ has/have exceeded scatter radiation as the most common form of noise appearing in the final displayed image.

Mottle

3 multiple choice options

Mathematically, the contrast present in any radiographic image is best thought of as the between two adjacent areas of different tonal value (density)

Divided ratio

3 multiple choice options

Electronic "snow" on a display monitor or TV monitor image is a form of

Noise

3 multiple choice options

Although both appear dark overall on conventional film, a truly fogged radiographic image differs from an overexposed image in that the fogged image

Displays no white areas

3 multiple choice options

Superimposed tissues which are not of present diagnostic interest may be considered as a form of

Noise

3 multiple choice options

Taken together, brightness, contrast, and noise make up the _____ functions of any image.

Visibility

3 multiple choice options

The ability to distinguish two adjacent details as being separate and distinct from each other defines image

Resolution

3 multiple choice options

An original exposure used an SOD of 80 cm and an OID of 4 cm. If the OID is increased to 6 cm, to what fraction of the original sharpness will the sharpness be reduced?

0.67

The formula FS x OID/SOD is used to calculate the _____ in a radiographic image.

Unsharpness

3 multiple choice options

What is the relative sharpness for an SOD of 70 cm and an OID of 10 cm?

7

Which of the following formulas would be correct for calculating the relative sharpness of a projected image?

SOD/OID

3 multiple choice options

The complete or "true" image shadow of a radiographic image is called its

Umbra

3 multiple choice options

For the image of an object to be shape distorted, its length and its width must be altered by

Different degrees

3 multiple choice options

Penumbra occurs in all radiographic images because

X-rays emanate from an area source

3 multiple choice options

Foreshortening is a form of

Distortion

3 multiple choice options

An object is projected using an SID of 180 cm and an SOD of 135 cm. If the projected image measures 20 cm in length, how big must the object have been?

15

When a 1 mm focal spot is used with an SID of 100 cm and an OID of 50 cm, the amount of penumbra present in the image will be

1

The overall resolution of an image depends upon

All of these

3 multiple choice options

What is the amount of unsharpness for a projection taken with an 0.3 mm focal spot, 76 cm SOD and 4 cm OID?

0.016

The unsharpness in an image is produced by all of the following except

mAs

3 multiple choice options

Which of the following should always be maximized?

Sharpness

3 multiple choice options

By selecting a particular mA station, one of a series of electrical _____ in the x-ray machine circuit is being engaged.

Resistors

3 multiple choice options

If the mA is set at 300 and the total mAs produced is 15 mAs, the exposure time must be

1/20 second

With all other factors unchanged, if mAs is increased by 50%, subject contrast in the remnant beam will

Not change at all

3 multiple choice options

To obtain 20 mAs using the 400 mA station, use an exposure time of _____ seconds.

0.05

The decimal exposure time 0.167 second is equal to which fractional time

1/6 seconds

To obtain 30 mAs using the 75 mA station, use an exposure time of _____ seconds.

0.4

To make a significant increase in the intensity of the remnant x-ray beam, mAs would need to be increased by at least

35%

3 multiple choice options

For a particular amount of x-ray exposure, mA and exposure time are _____ to each other.

Inversely proportional

3 multiple choice options

The fractional time 1/120 second is equal to _____ milliseconds.

8.3

To obtain 70 mAs using the 200 mA station, use an exposure time of _____ seconds.

0.35

Especially for digital images, insufficient mAs can be a prime contributor to _____ in the image.

Quantum mottle

3 multiple choice options

If the mA is tripled, how must the exposure time be adjusted to maintain the original x-ray beam intensity?

Cut it to 1/3

1 multiple choice option

To obtain 240 mAs using the 300 mA station, use an exposure time of _____ seconds.

0.8

With an 80-kVp x-ray beam doubling the mA would double the number of which photons in the primary x-ray beam?

All of these

3 multiple choice options

All other factors equal, when mAs is reduced, the photoelectric/Compton ratio will

Remain unchanged

2 multiple choice options

High-kVp techniques allow more margin for error in estimating mAs values. This margin of error is called

Exposure latitude

3 multiple choice options

The minimum kVp is defined as the lowest kVp that provides some degree of x-ray penetration through _____ in the body part being radiographed.

All tissues of interest

What is the effect of increasing kVp upon sharpness of detail in the image?

It is not related to sharpness

Which of the following is not a reason why higher kVp levels reduce subject contrast in the remnant x-ray beam?

More scatter radiation is produced within the patient

When the kVp is increased, overall exposure at the image receptor plate increases because

All of these

The x-ray beam has higher average energy

The x-ray beam penetrates more through tissues

More x-rays are emitted from the x-ray tube

The effect of kVp on the intensity of the remnant x-ray beam is

Exponential

When radiographing the lungs or small body parts, which of the following best describes the effect of using high kVp techniques on scatter radiation?

They increase scatter, but not substantially

What has been the impact of digital imaging technology upon the use of high-kVp techniques?

It has made them more relevant, and more practical to apply

To increase the subject contrast in the remnant beam, you must

Reduce Compton interactions more than you reduce photoelectrics

For an AP lumbar spine projection, an original technique of 40 mAs at 80 kVp, which produced a proper exposure, is adjusted using the 15% rule in a series of steps to 160 mAs at 58 kVp. For an average patient, which of the following would result?

Underexposure at the receptor plate

In order to double the remnant x-ray beam signal reaching the image receptor, rather than using mAs, if the kVp is increased by 15% instead, patient exposure will

Increase by 25-40%

Starting at 40 kVp, in order to double the overall exposure at the image receptor plate, change kVp by

6 kVp increase

Most essential to producing a radiographic image is adequate

Penetration

Generally, anything that lengthens the gray scale within the remnant x-ray beam signal also increases

Exposure latitude

In terms of overall exposure to the imaging receptor, which of the following techniques is not roughly equivalent to the other four?

400 mA, 0.l7 sec., 80 kVp

A wedge-shaped compensating filter would always be placed with the thickest end

Toward the thinnest anatomy

When changing from a fully-rectified single-phase x-ray machine to a half-rectified machine, what change in technique would be required to maintain overall exposure at the image receptor?

2 times

Protective filtration in the x-ray tube and collimator do all of the following to the x-ray beam except

Increase its peak energy

For a particular set kVp, which type of x-ray equipment produces the very highest average kV for the x-ray beam?

Battery-powered mobile units

Three-phase and high-frequency generators can produce a much more continuous output of x-rays over time, due to

Overlapping pulses of electricity

Which type of x-ray machine generator produces an average kV at about 91% of the set kVp?

3-phase, 6-pulse

With all other factors unchanged, if 0.5 mm of general filtration is added to the collimator, image sharpness of detail will

Not change at all

The half-value layer (HVL) is used to measure

The degree of penetration of the x-ray beam

Default digital processing can balance the brightness across the image so well that it has reduced the need for using _____ except in the most extreme cases.

Compensating filtration

Compared to a 3-phase 6-pulse x-ray machine, a 3-phase 12-pulse unit is

Slightly more efficient

When the field size is opened to a much larger area, the total amount of radiation striking each square inch (or square cm) of the receptor plate within the field is

Increased

The field size is changed from 35 X 43 cm to 20 X 24 cm. Which of the following adjustments in radiographic technique would maintain the overall exposure at the image receptor?

30-50% increase

Positive beam limitation (PBL) should be manually overridden when

The desired field size is smaller than the receptor plate size

Off-focus radiation is

Primary radiation

When the body part being radiographed is much smaller than the image receptor plate, the edges of the field should be collimated

To allow 1/2 inch of field beyond each edge of the anatomy

Which of the following devices is most recommended for both protecting the patient and improving subject contrast in the remnant beam as it reaches the image receptor

Collimator

As field size is increased, which aspect of the remnant beam signal reaching the image receptor actually decreases

Subject contrast

Modern x-ray collimators have two sets of shutters. The second (lower) set is actually a patient protection device which reduces

Off-focus radiation

When the field is collimated to a smaller size, the overall exposure reaching the image receptor plate decreases. This is primarily due to a reduction in

Scatter radiation

A leaded rubber sheet placed behind the patient's back during a lateral projection of the lumbar spine prevents

Scatter radiation from being produced in the tabletop

For a patient with padded dash syndrome or a chicken bone lodged in the neck, use

A 20% reduction in kVp only

What technique increase is recommended for an extremity in a pure fiberglass cast?

No increase is needed

With the exception of esophagrams, what is the optimum kVp for solid-column barium procedures?

110-120

Which of the following would be considered an additive disease?

Increase in mineral content

Compared to the usual AP supine chest technique for living patients, the radiographic technique for an AP supine chest taken on a dead body would be

Increased